The Guardian view on genetics: diversity is destiny | Editorial

Same sex attraction isn't genetic. It's human

The argument that some behaviour is "in our genes" is distrusted by the left. Too often it is used to whitewash terrible injustices. Yet it cannot be entirely dismissed. Certain patterns of behaviour and thought, such as the faculty of language acquisition, are very clearly a part of our genetic inheritance as a species. The instinct for justice itself appears to arise spontaneously in small children. The escape from the idea that genes determine our fate is not to pretend that they have no influence, but to come to understand that they can have many different, often conflicting influences, even within the same people and certainly within populations. This is true both of their effects on behaviour and on bodies.

Biology is a science that deals with variations. There is no one perfect type of a species. Diversity, in this sense, is not just something to aim at but something necessary for a population to flourish. The idea that natural selection works only on mutations is a deeply misleading oversimplification. It is much more likely to alter the proportions of an already existing mixture of genes. What is more, game theory shows that the balance of advantage will shift as a result of the shift in a gene's frequency. With very few exceptions, such as the change that Noam Chomsky postulates makes possible the complexity of human syntax, few mutations are going to be so overwhelmingly advantageous that they drive out all other variants. More often, if any one variation becomes dominant, there will be an advantage for its opposite. "Normal" is thus a shifting, fuzzy category.